If the leather isn't brittle then a gentle buff with a clean duster and some kind of solid polish will be all it needs. If you think the leather is thirsty or brittle you could even try a bit of vaseline - try an out-of-the way area and see how it comes up. But remember that anywhere to be sat on needs to have any polish well soaked in and well buffed off or it will come off on bottoms.
The legs might have layers of wax polish built up, so a gentle wipe with a etergent solution, rinse and light furniture polish shoudl sort it.